1. Field of the Invention
The present invention generally relates to a camera apparatus and, more particularly, to a camera apparatus having a control function for releasing a limitation in release operation in accordance with the will of a photographer even when proper photographing cannot be performed depending on photographing conditions, or for changing a shutter release timing in accordance with the taste or skill of a photographer in order to reduce a camera shake which is a problem in photographing.
2. Description of the Related Art
Recently, since a camera has various automatic functions such as an automatic exposure function and an automatic focusing function, a photographer can take a proper picture in almost any case by simply depressing a release button. Since such an automatized camera gives priority to taking a proper picture, if no proper photographing conditions can be obtained, the camera inhibits a release operation or alarms a photographer with illumination of a light-emitting diode or sound, thereby informing the photographer that a change in photographing conditions, manual focus adjustment, or the use of an electronic flash is required.
One cause of degrading the quality of a picture is a phenomenon called "camera shake". One proposed camera delays or inhibits a release operation, if this camera shake is large, until the camera shake reaches its peak value or becomes small.
However, when the release operation is delayed or inhibited in a camera as described above, a release time lag is extremely prolonged to sometimes miss a spontaneous shutter chance. In such a case, a photographer is forced to change photographing conditions, manually performs focus adjustment, uses an electronic flash (waits for charge completion), ensures holding of the camera, or fixes the camera by a tripod.
In order to prevent the above inconveniences, there is a camera by which a photographer can select, by a button operation, a mode in which a release operation is neither delayed nor inhibited. Although this camera can perform real-time photographing, it performs photographing by a normal release feeling even if there is a factor having a large influence on a picture, such as underexposure, an out-of-focus state, and a large camera shake. For this reason, a photographer may not notice that a taken picture is an improper one or must ignore an alarming light-emitting diode or the like turned on in a finder. In addition, a camera of this type requires a button operation or the like for mode selection, and this operation is time-consuming.
A release operation of a camera is largely affected by various factors such as the shape, the stroke, and the depression force of a release button. This release operation is assumed to be one factor of causing a camera shake in photographing by a camera, and in order to reduce the camera shake, the stroke is extremely shortened or the depression force is reduced in conventional methods.
In order to reduce the camera shake, various types of cameras have been proposed. Examples are a camera in which a release operation is activated when a user releases his or her finger from a portion corresponding to a release button, a camera in which a release operation is activated when an intentional wink of a user is detected, and a camera having two or more release buttons in its upper and lower portions so that a force applied on the camera is uniformly distributed with a good balance because a user must depress the two or more buttons, thereby reducing the camera shake.
Published Unexamined Japanese Patent Application No. 54-33030 discloses a camera which shortens the stroke by using a pressure-sensitive semiconductor device, thereby preventing the camera shake. In addition, Published Examined Japanese Utility Model Application No. 58-37056 discloses a camera in which release button units having different depression forces and strokes of a release and different photographing operation timings can be selected.
In conventional release button structures, however, although the shape, the stroke, and the depression force of the release button are different between the respective types of cameras, they are almost predetermined in individual cameras. That is, although the stroke may be extremely shortened, the depression force may be reduced, or the release button unit may be exchanged, in order to reduce the camera shake, these conditions are predetermined in individual cameras.
In current camera apparatuses, however, the use of a zoom lens which covers focal length: f=100 [mm] to 150 [mm] is generally considered, an influence of an image shake caused by the camera shake must be taken into consideration more seriously. However, the release conditions (the shape, the stroke, and the depression force) which are assumed as one cause of the camera shake are not determined by taking the photographing level (skill) of each user into consideration but is unconditionally provided to users by manufacturers.
In addition, as described above, although the camera shake can be prevented by shortening the stroke or reducing the depression force, an inconvenience of causing an erroneous release operation (erroneous photographing) caused by an erroneous operation is increased to lead to waste of a film. More specifically, since a timing at which a first release switch is turned on is set close to a timing at which a second release switch is turned on, a user turns on both the first and second release switches although he or she intends to turn on only the first one.
Furthermore, in conventional cameras, the timings at which the first and second release switches are turned on cannot be independently adjusted.